117P Pretherapeutic neutrophil-lymphocyte ratio as prognostic and predictive factors in metastatic breast cancer treated with cyclin dependent kinase 4/6 inhibitors

Cyclin dependent kinase inhibitors (CDK4/6i) changed the course of HER2-negative (HER2-) hormone receptor positive (HR+) metastatic breast cancer (mBC). To date, no factors have been shown to predict a better response to CDK4/6i. The neutrophil-lymphocyte ratio (NLR), reflects of the host systemic inflammatory response, is an independent prognostic factor for recurrence and survival in some solid cancers. The aim of our study was to assess the prognostic and predictive impact of NLR in mBC patients treated with first line CDK4/6i. Retrospective single center study including mBC patients treated with first line CDK4/6i between November 2015 and December 2019. Progression free survival (PFS) and overall survival (OS) were assessed according to NLR. A total of 126 patients treated with palbociclib (n=101), ribociclib (n=18) or abemaciclib (n=7) were included, with a median follow up of 16 months. Median age was 65 years. Majority of the population (88%) had good performance status (0-1). Twenty percent of patients had visceral metastases without bone lesion. The pretherapeutic NLR cutoff was 2.53. High NLR was significantly associated with worse PFS (hazard ratio (HR) = 0.52 [confidence interval 95% = 0.29-0.94], p = 0.027). At the time of our analysis, median OS was not reached. High NLR was predictive of early progression with progressive disease for 8 patients at first evaluation versus 2 patients in low NLR group, moreover complete responses were more frequent in low NLR group (p=0.03). Our findings suggest that high NLR is associated with worse PFS and might be prognostic of early progression in HER2- HR+ mBC patients. NLR is an easily accessible prognostic and predictive marker in clinical practice. These results need to be confirmed in large prospective study.